Elastic body for blades and cleaning blade using this elastic body

Abstract

The present invention addresses the problem of providing a cleaning blade having excellent durability. As a solution, provided is an elastic body for blades in which a contact part contains a polyurethane containing a reactive silicone, and the reactive silicone has a phenyl group and two or more active hydrogen groups.

Description

Elastic body for blade and cleaning blade having the elastic body

[0001] The present invention relates to an elastic body for a blade used in an electrophotographic apparatus, and a cleaning blade having the elastic body for a blade.

[0002] Electrophotographic devices such as copiers, printers, facsimiles, and multifunction devices use blades such as cleaning blades, developing blades, conductive blades, polishing blades, and coating blades. Blades consist of an elastic body and a support member, and the elastic body is typically made of a thermosetting polyurethane having appropriate hardness and elasticity. In recent years, there has been a demand for longer life for components such as blades in electrophotographic devices to reduce the frequency of photoreceptor unit replacement. Furthermore, there is a demand for blade elastic bodies that contribute to the long life of the entire system by preventing filming (adhesion) of toner, external additives, etc., on the photoreceptor drum and reducing photoreceptor drum wear.

[0003] In order to extend the life of the blade, a method of increasing the hardness of the contact portion that contacts the photosensitive member or the like has been proposed. For example, Patent Document 1 proposes an elastic body in which the edge layer (contact portion) and the base layer (back portion) are formed from different polyurethane materials, and only the edge layer is made to have a high hardness. Patent Document 2 also proposes an elastic body in which only the image carrier contact portion of an elastic body made of a single polyurethane is impregnated with an isocyanate compound, thereby increasing the hardness of only the image carrier contact portion. Furthermore, in Patent Document 3, the applicant proposes a cleaning blade that uses polyurethane urea using a specific diaminobenzoic acid ester-based curing agent, and has higher hardness and durability than other polyurethanes or polyurethane ureas.

[0004] Japanese Patent No. 4818945 Japanese Patent Application Laid-Open No. 2005-156696 Japanese Patent Application Laid-Open No. 2019-197175

[0005] An object of the present invention is to provide a cleaning blade having excellent durability.

[0006] The means for solving the problems of the present invention are as follows: 1. An elastic body for a blade, wherein the contact portion contains polyurethane containing reactive silicone, and the reactive silicone has a phenyl group and two or more active hydrogen groups. 2. The elastic body for a blade described in 1., wherein the reactive silicone further has a methoxy group. 3. The elastic body for a blade described in 1. or 2., wherein the back portion contains a polymer compound having a different composition from that of the contact portion. 4. A cleaning blade, wherein the elastic body for a blade described in any of 1. to 3. is attached to a support member.

[0007] The elastic body for blades of the present invention has excellent durability.

[0008] 10 is a schematic diagram of an elastic body for a blade in which the contact portion and the back surface portion have different compositions.

[0009] The blade elastic body of the present invention (hereinafter simply referred to as "elastic body") has a contact portion containing polyurethane containing reactive silicone, and this reactive silicone has a phenyl group and two or more active hydrogen groups. The size of the blade elastic body is not particularly limited, but for example, the width is about 5 mm to 20 mm and the thickness is about 1 mm to 3 mm. The length of the elastic body is selected appropriately depending on the width of the paper to be printed, but for example, it is about 220 mm when used for A4-size paper.

[0010] In the blade elastic body of the present invention, the abutting portion contains a polyurethane containing a specific reactive silicone. Specifically, the abutting portion is made of a cured material composition containing at least a polyol, a polyisocyanate, and a reactive silicone. The blade elastic body of the present invention may be made entirely of a cured material composition of a single composition, or the back portion may be made of a cured material composition of a different composition from the abutting portion. When the back portion is made of a cured material composition of a different composition from the abutting portion, the polymer compound contained in the material composition constituting the back portion is preferably one that can form a covalent bond with the polyurethane contained in the abutting portion, specifically, polyurethane, polyurea, or polyurethane urea.

[0011] 1 shows a schematic diagram of an elastic body for a blade in which the contact portion and the back portion are different in composition. Examples of an elastic body for a blade 1 in which the contact portion 11 and the back portion 12 are different in composition include a structure in which the contact portion 11 is provided on the entire surface of one of the elastic bodies for a blade 1 (e.g., FIG. 1A ), and a structure in which the contact portion 11 is provided along only one long side of the elastic body for a blade 1 (e.g., FIG. 1B ). When the contact portion 11 and the back portion 12 are made of different compositions, it is preferable that the contact portion 11 and the back portion 12 have different colors in order to improve workability and reduce work errors when joining the elastic body for a blade 1 to a support member.

[0012] Polyols can be any polyol used as a polyurethane material, including polyether polyols, polyester polyols, and polycarbonate polyols. Two or more compatible polyols can also be used in combination. The number-average molecular weight of these polyols is preferably 1,000 to 4,000.

[0013] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0014] Examples of polyester polyols include those obtainable by reacting a dicarboxylic acid with a glycol according to a conventional method. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid; oxycarboxylic acids such as oxybenzoic acid; and ester-forming derivatives thereof. These may be used alone or in combination of two or more. Examples of glycols include aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, and triethylene glycol; alicyclic glycols such as 1,4-cyclohexanedimethanol; aromatic diols such as p-xylenediol; and polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These may be used alone or in combination of two or more.

[0015] Other examples of polyester polyols include those obtainable by ring-opening polymerization of lactones using diols as initiators. Examples of diols include ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, 4-oxa-2,6-heptanediol, 4-oxaheptane-1,7-diol, and 1,10-decanediol. These may be used alone or in combination of two or more. Examples of lactones include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, and β-methyl-δ-valerolactone. These may be used alone or in combination of two or more.

[0016] Examples of polycarbonate polyols include reaction products of dialkyl carbonates and diols. Examples of dialkyl carbonates include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate. These may be used alone or in combination of two or more.

[0017] Examples of diols include 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, neopentyl glycol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,2'-bis(4-hydroxycyclohexyl)-propane, etc. These may be used alone or in combination of two or more.

[0018] Polyisocyanate: Any polyisocyanate that is used as a polyurethane material can be used without any particular limitation, and examples thereof include 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), carbodiimide-modified MDI, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 3,3'-bitrylene-4,4'-diisocyanate, and 3,3'-dimethyldiphenylmethane diisocyanate. Examples of the diisocyanates include diisocyanates such as 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate uretidinedione (a dimer of 2,4-TDI), metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, orthotolidine diisocyanate, xylene diisocyanate, paraphenylene diisocyanate, and lysine diisocyanate; triisocyanates such as triphenylmethane-4,4',4"-triisocyanate; and polymeric MDI. These may be used alone or in combination of two or more.

[0019] Reactive Silicone The reactive silicone used in the present invention has a phenyl group and two or more active hydrogen groups. The number of these functional groups refers to the number of functional groups per molecule, and if the number of functional groups per molecule varies, it refers to the average value. Because the reactive silicone has a phenyl group, it has improved compatibility with polyurethane, making it less likely for the silicone moiety to aggregate in the polyurethane. The reactive silicone preferably has one or more phenyl groups, more preferably 1.5 or more, and even more preferably two or more. The active hydrogen groups of the reactive silicone react with isocyanate groups to form urethane bonds or urea bonds, which are incorporated into the polyurethane. Examples of active hydrogen groups include hydroxyl groups, amino groups, imino groups, carboxy groups, urethane groups, and urea groups. Among these, hydroxyl groups and amino groups are preferred because they result in superior physical properties for the resulting polyurethane. The reactive silicone preferably has 2.5 or more active hydrogen groups, more preferably 3 or more, even more preferably 3.5 or more, and even more preferably 4 or more.

[0020] The elastic body for blades of the present invention is excellent in the friction-reducing effect derived from the silicone moiety because the reactive silicone is less likely to aggregate. Furthermore, the elastic body for blades of the present invention is excellent in durability because the reactive silicone is fixed in the polyurethane by forming a covalent bond, thereby maintaining the friction-reducing effect for a long period of time. In the present invention, the amount of reactive silicone to be added is not particularly limited as long as it does not impair the effects of the present invention, but it is preferable to add 0.1 to 10 wt % of the reactive silicone to the total amount of polyurethane, for example.

[0021] Furthermore, the reactive silicone used in the present invention preferably has a methoxy group. The methoxy group can undergo dehydration condensation to form a covalent bond between methoxy groups in the silicone or with a hydroxyl group in the polyurethane, so further improvement in durability can be expected. The reactive silicone preferably has one or more methoxy groups, more preferably has 1.5 or more methoxy groups, and even more preferably has two or more methoxy groups.

[0022] As the curing agent, either an alcohol-based curing agent or an amine-based curing agent, or both, can be used. The curing agent is optional and may not be used. Examples of alcohol-based curing agents include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2-isopropyl-1,4-butanediol, and 3-methyl-2,4-pentanediol. 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 1,7-heptanediol, 3,5-heptane aliphatic dihydric alcohols such as diol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; alicyclic dihydric alcohols such as cyclohexanedimethanol (for example, 1,4-cyclohexanedimethanol), cyclohexanediol (for example, 1,3-cyclohexanediol, 1,4-cyclohexanediol), and 2-bis(4-hydroxycyclohexyl)-propane; and trihydric or higher polyhydric alcohols such as trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, polyglycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, dipentaerythritol tetramethylolpropane, triethanolamine, and triisopropanolamine. These may be used alone or in combination. Among these, 1,4-butanediol is preferred as the dihydric alcohol, and trimethylolpropane is preferred as the trihydric alcohol.

[0023] Examples of the amine-based curing agent include diamines such as ethylenediamine, hexamethylenediamine, diethyltoluenediamine, isophoronediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, and 4-chloro-3,5-diaminobenzoic acid isobutyl, and these can be used alone or in combination of two or more.

[0024] Catalysts can also be used to accelerate the curing reaction. The catalyst is not particularly limited as long as it accelerates the urethanization of a hydroxyl group and an isocyanate group, or the ureaization of an amino group and an isocyanate group, and examples thereof include trialkylamines such as triethylamine; tetraalkyldiamines such as N,N,N',N'-tetramethyl-1,3-butanediamine; aminoalcohols such as dimethylethanolamine; ethoxylated amines; ethoxylated diamines; ester amines such as bis(diethylethanolamine) adipate; triethylenediamine; cyclohexylamine derivatives such as N,N-dimethylcyclohexylamine; morpholine derivatives such as N-methylmorpholine and N-(2-hydroxypropyl)-dimethylmorpholine; piperazine derivatives such as N,N'-diethyl-2-methylpiperazine and N,N'-bis-(2-hydroxypropyl)-2-methylpiperazine; and amine compounds such as dibutyltin di dialkyltin compounds such as laurate and dibutyltin di(2-ethylhexoate); organic tin compounds such as stannous 2-ethylcaproate and stannous oleate; organic bismuth compounds such as bismuth 2-ethylhexanoate and bismuth neodecanoate; saturated fatty acid alkali metal salts, which are salts of saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid with alkali metals such as lithium, sodium, potassium, rubidium, cesium, and francium; and temperature-sensitive catalysts such as diazabicyclononene (DBN), diazabicycloundecene (DBU), and phenolic resin salts thereof, octylate salts, stearates, oleates, formates, and p-toluenesulfonates.

[0025] Other Components The resin composition for forming the polyurethane contained in the contact portion may contain additives such as fillers, stabilizers, reactivity-promoting catalysts, softeners, processing aids, mold release agents, antifoaming agents, and flame retardants, as needed.

[0026] In the polyurethane contained in the contact portion of the elastic body for a blade of the present invention, the molar ratio of the active hydrogen groups of the polyol, reactive silicone, and curing agent to the isocyanate groups of the polyisocyanate or prepolymer is preferably 0.8 or more and 1.0 or less, more preferably 0.85 or more and 0.98 or less, and even more preferably 0.85 or more and 0.95 or less.

[0027] The method for producing the elastic body for blades of the present invention is not particularly limited, and it can be produced by a centrifugal molding method, or the methods disclosed in Japanese Patent Nos. 4018033, 4820161, and 4974490 filed by the present applicant. The molding method may be any of a one-shot method, a prepolymer method, and a quasi-prepolymer method.

[0028] In the one-shot method, a polyol, polyisocyanate, curing agent, catalyst, etc. are added all at once and cured to produce a molded thermosetting polyurethane urea. In the prepolymer method, a polyol is reacted with a stoichiometrically equivalent or excess amount of polyisocyanate to prepare a prepolymer having an isocyanate group at its terminal, and a predetermined amount of curing agent, catalyst, etc. is mixed thereto to cure the prepolymer to produce a molded thermosetting polyurethane urea. In the quasi-prepolymer method, a portion of the polyol is mixed with the curing agent in advance, and a prepolymer is prepared with the remaining polyol and polyisocyanate. The premixed mixture of polyol, curing agent, catalyst, etc. is mixed thereto and cured to produce a molded thermosetting polyurethane urea.

[0029] The elastic body for blades of the present invention preferably has an international rubber hardness (IRHD) of the contact portion of 60 or more and 100 or less. The elastic body for blades of the present invention preferably has a rebound resilience of 10% or more and 60% or less, measured in accordance with JIS K 7312-1996.

[0030] A blade can be manufactured by attaching the elastic material for a blade of the present invention to a support member made of metal or the like. The use of the blade of the present invention is not particularly limited, and it can be used as a cleaning blade, a developing blade, a conductive blade, a polishing blade, a coating blade, etc. Among these, the elastic material for a blade of the present invention is suitable for use as a cleaning blade because of its excellent durability.

[0031] Prepolymer Production Example 1 Polycaprolactone (Daicel Corporation, PLACCEL 220, hydroxyl value 56.1 mgKOH / g) was used as the polyol. This was dehydrated under reduced pressure at 110°C for 2 hours. To 100 parts by weight of this polyol, 83.5 parts by weight of 4,4'-diphenylmethane diisocyanate (MDI) (Tosoh Corporation, MILLIONATE MT) was added as the polyisocyanate, and the mixture was reacted at 80°C for 3 hours in a nitrogen atmosphere to obtain a prepolymer with an NCO% of 13.0.

[0032] Example 1 100 parts by weight of the above prepolymer was vacuum degassed at 75°C, to which 43.9 parts by weight of a polyol (Daicel Corporation, PLACCEL 220) that had been similarly degassed was added, followed by 7.2 parts by weight of a reactive silicone having one or more phenyl groups, two or more hydroxyl groups, and one or more methoxy groups (Shin-Etsu Chemical Co., Ltd., X-48-1903S, hydroxyl value 112 mgKOH / g). 9.5 parts by weight of a mixture of 1,4-butanediol:1,1,1-trimethylolpropane = 75:25 (weight ratio) was added as a curing agent, and the mixture was stirred with an agitator. The mixture was poured into a centrifugal molding machine at 150°C, demolded after 1 hour, post-crosslinked at 120°C for 12 hours, and aged at room temperature for 7 days to obtain a sheet having a thickness of 1.9 mm.

[0033] Example 2 A 1.9 mm thick sheet was obtained in the same manner as in Example 1, except that the reactive silicone was a silicone having one or more phenyl groups and two or more amino groups (X-22-9409, manufactured by Shin-Etsu Chemical Co., Ltd., functional group equivalent: 670 g / mol) and the curing agent amount was as shown in Table 1.

[0034] Comparative Example 1: A sheet having a thickness of 1.9 mm was obtained in the same manner as in Example 1, except that no reactive silicone was added and the amount of curing agent was used as shown in Table 1. Comparative Example 2: A sheet having a thickness of 1.9 mm was obtained in the same manner as in Example 1, except that the reactive silicone was changed to a silicone having two or more hydroxyl groups (DOWSIL (registered trademark) BY 16-201, manufactured by Dow-Toray Industries, Inc., functional group equivalent weight 750 g / mol) and the amount of curing agent was used as shown in Table 1.

[0035]

[0036] The sheets obtained in the examples and comparative examples were cut to form elastic bodies for blades, which were then bonded to a metal support made of a steel plate having a thickness of 2.0 mm with a dimer acid-based hot melt adhesive to prepare cleaning blades.

[0037] <Durability Evaluation> The cleaning blade was attached to a color printer (DocuPrint C4000d, manufactured by Fujifilm Business Innovation Co., Ltd.), and a paper feed test was conducted at 28°C and 85% RH. Durability was evaluated based on the number of sheets of paper passed before an image defect due to toner passing through occurred, which was caused by damage to the blade edge. Specifically, when the blade edge is damaged, toner passes through the damaged area, causing the toner to adhere to the charging roller and stain it. The area of ​​the charging roller where the toner adhered is not charged, causing white spots in the image. The results are shown in Table 2.

[0038] The elastic material for blades obtained in Comparative Example 1, which did not contain reactive silicone, printed 10,000 sheets, and the elastic material for blades obtained in Comparative Example 2, which contained reactive silicone without a phenyl group, printed 50,000 sheets, after which image defects due to blade damage occurred. In contrast, the elastic material for blades obtained in the Examples of the present invention was able to print over 200,000 sheets without any image defects.

[0039] 1 Elastic body for blade 11 Contact portion 12 Back portion

Claims

1. An elastic body for blades, characterized in that the contact portion contains polyurethane containing reactive silicone, and the reactive silicone has a phenyl group and two or more active hydrogen groups.

2. The elastic body for blades according to claim 1, wherein the reactive silicone further comprises a methoxy group.

3. The elastic body for a blade according to claim 1, characterized in that the back portion contains a polymer compound having a different composition from that of the contact portion.

4. A cleaning blade, characterized in that the elastic body for a blade according to any one of claims 1 to 3 is attached to a support member.

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